# symmetry vs. slip Bounday condition

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 April 28, 2009, 06:45 symmetry vs. slip Bounday condition #1 New Member   sungho yoon Join Date: Mar 2009 Posts: 20 Rep Power: 15 I'm not quite sure what is the difference between symmetry boundary condition and slip boundary condition. According to my understanding, both of them applies zero to normal component and zero gradient to tangential component. dont' they? Then, what is the difference? Regards, Sungho

 February 22, 2012, 06:15 #2 Senior Member   Anne Gerdes Join Date: Aug 2010 Location: Hamburg Posts: 168 Rep Power: 14 Hey, I am asking myself the same question. Is there an answer already? Kind Regards Anne

 February 22, 2012, 07:20 #3 Senior Member   Felix L. Join Date: Feb 2010 Location: Hamburg Posts: 165 Rep Power: 16 Hi, there, the slip and symmetry BCs are numerically the same. There can be a difference in how OpenFOAM treats these boundaries in pre- and post-processing, respectively. I.e. slip can be applied to wall-type-boundaries and the wall-only post-processing applications (wallGradU for example) can still be used. Greetings, Felix. kiddmax, fumiya, hua1015 and 9 others like this.

 February 22, 2012, 08:15 #4 Senior Member   Anne Gerdes Join Date: Aug 2010 Location: Hamburg Posts: 168 Rep Power: 14 Thank you for this fast answer, Felix!

 August 30, 2012, 09:07 boundary condition (symmetry vs periodic doubt) #5 Senior Member   kunar Join Date: Nov 2011 Posts: 117 Rep Power: 12 Dear friends, i am doing 3D wing analysis, i have doubt on boundary conditions in fluent ie both symmetry and periodic, anybody have the answer please let me know briefly,for what kind of purpose to use symmetry & periodic boundary conditions, please tell any example with problem.

April 30, 2013, 02:01
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Quote:
 Originally Posted by FelixL Hi, there, the slip and symmetry BCs are numerically the same. There can be a difference in how OpenFOAM treats these boundaries in pre- and post-processing, respectively. I.e. slip can be applied to wall-type-boundaries and the wall-only post-processing applications (wallGradU for example) can still be used. Greetings, Felix.
hi Felix,
would you please explain us more; about how difference OpenFOAM treats these boundaries (symmetry and slip)?
thank you very much
i have an airfoil, i set the inlet boundary velocity inlet, and the outlet boundary pressure outlet, i doubt about defining the up and down surface of my airfoil symmetry or slip?
thanks a lot again Felix.

 December 14, 2018, 22:46 #7 Senior Member   Join Date: Jan 2013 Posts: 134 Rep Power: 11 I can understand symmetry on a plane patch. But if slip is identical to symmetry condition, what does it mean to use slip on a curved or a closed surface, like a circular cylinder?